In design and development of a control system and an embedded system in the automobile industry, the electronics/precision industry, or the like, various documents, such as specification documents, design documents, or test specification documents, generated through design and development processes are managed. Therefore, in the system design, in some cases, a file management apparatus manages a large number of documents.
The file management apparatus can store information on association between files through a file association process performed by an operator. In this configuration, when one of the files is modified, the file management apparatus can search for a file influenced by the modification.    Patent Literature 1: Japanese Laid-open Patent Publication No. 2002-149648
However, to associate files, the operator searches for related portions by referring to each of the files, and associate the files with the related portions. Therefore, it takes effort and time to associate the files. For example, if a document is generated in a table format file, related portions are searched for from a large number of cells; therefore, it is cumbersome to search for the related portions.